Repeater system and method

ABSTRACT

Repeater systems and methods are disclosed. In one embodiment, a repeater system located within a coverage area comprises: a host configured to combine multiple downlink signals from multiple communication sources located outside the coverage area into a first combined downlink signal; at least one remote coupled to the host and configured to transmit the first combined downlink signal as a second downlink RF communication signal to terminals within the coverage area. The at least one remote is configured to produce a combined uplink signal from multiple uplink signals received through multiple communication links from the terminals, and configured to forward the combined uplink signal to the host. The host produces multiple signals from the combined uplink signal for transmission to the multiple communication sources, wherein a first of the plurality of terminals communicates with a different one of the multiple communication sources than a second of the plurality of terminals.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of U.S. patentapplication Ser. No. 14/898,712 titled “REPEATER SYSTEM AND METHOD”,which is a National Stage 371 Application of International ApplicationNo. PCT/IB2014/062297 titled “REPEATER SYSTEM AND METHOD” filed Jun. 17,2014, which claims the benefit of and priority to European PatentApplication No. 13173568.0, filed Jun. 25, 2013 and titled “REPEATERSYSTEM”, the contents of each of which are incorporated herein byreference.

DESCRIPTION

The invention relates to a repeater system according to the preamble ofclaim 1 and to a method for operating a repeater system.

A repeater system of this kind comprises a front end section and a backend section. The front end section herein is constituted to, in adownlink direction, receive signals from at least one communicationsource located outside of a coverage area of the repeater system and to,in an uplink direction, transmit signals to the at least onecommunication source. The back end section in turn is constituted to, inthe downlink direction, transmit an RF communication signal into thecoverage area and to, in the uplink direction, receive an RFcommunication signal out of the coverage area.

A repeater system of this kind may for example be installed in a mobileenvironment such as a train, a plane, a ship, a bus or the like toprovide coverage on the inside of the mobile environment. A repeatersystem of this kind may also be installed in a stationary environmentwhich is, at least to some extent, shielded from the outside, such as abuilding, a tunnel or the like. The repeater system in this caseprovides coverage on the inside of the shielded environment.

A conventional repeater system, as it is for example known from EP 1 109332 A2, serves to repeat radial frequency (RF) signals to for exampleprovide coverage in an isolated or shielded environment or to improvecoverage in areas in which the signal strength is weak and/or dedicatedbands, sub-bands or carriers shall be provided only. For this purpose,the digital repeater of EP 1 109 332 A2, in a downlink direction,down-converts a received analog RF signal and digitizes the RF signal inorder to process the digitized RF signal in the digital baseband. Theprocessed digitized RF signal is then converted into an analog signal,is up-converted and amplified and transmitted via a coverage antennainto the coverage area in which coverage is to be provided. Theprocessing in the uplink direction takes place in an analogous fashionincluding a digital baseband processing and a power amplification fortransmission to an outside communication source, for example a basestation.

Such repeater system, as it is for example known from EP 1 109 332 A2,is transparent for communication signals in that the RF signals outputto the coverage area equal the RF signals received from an outsidecommunication source (despite an amplification).

This has the effect—especially when such repeater systems are used in amoving environment such as a train, a ship, a plane or the like—that a(mobile) terminal in the coverage area having established acommunication link to an outside communication source via the repeatersystem must perform a hand-over operation if the signal strength of thecommunication link becomes weak, i.e. thesignal-to-noise-and-interference ratio (SNIR) of that communication linkbecomes small.

Further, a user of a terminal conventionally has subscribed for servicesof a signal operator such that he is bound to the services offered bythat operator. In case the repeater system (for example including adistributed antenna system for providing distributed coverage in thecoverage area) does not belong to that operator and hence does notprovide coverage for the services provided by that operator, the userpotentially must access the services of another operator by roaming,which may be limited and at the same time expensive.

It is an object of the instant invention to provide a repeater systemand a method for operating a repeater system which may provide anapproved coverage in a coverage area with the potential of high datarates for communication links in that coverage area.

This object is achieved by means of a repeater system comprising thefeatures of claim 1.

Specifically, within a repeater system it is provided that

-   -   in the downlink direction the front end section is constituted        to combine multiple signals from multiple communication sources        into a combined signal and to transmit the combined signal to        the back end section, wherein the back end section is        constituted to produce, from the combined signal, the RF        communication signal for transmission into the coverage area and    -   in the uplink direction the back end section is constituted to        produce, from a received RF communication signal, a combined        signal, wherein the front end section is constituted to produce        multiple signals from the combined signal received from the back        end section for transmission to the multiple communication        sources.

The repeater system hence comprises a front end section and a back endsection. In the downlink direction, the front end section combinessignals that are received from outside communication sources into acombined signal. Hence, multiple communication links established betweenoutside communication sources and the front end section are combined(aggregated) to a single combined signal using a link aggregationscheme. The combined signal is then transmitted to the back end section,and the back end section produces from the combined signal a common RFcommunication signal which is transmitted into the coverage area forproviding coverage in that coverage area.

In the uplink direction, in turn, the back end section produces acombined signal from an RF communication signal received out of thecoverage area. The received RF communication signal herein may beconstituted by multiple communication links between terminals located inthe coverage area and the back end section. The combined signal is thenforwarded to the front end section, which produces signals out of thecombined signals for transmission to the outside communication sources.

The front end section may for example, in one embodiment, comprise an RFprocessing unit together with a conversion and link aggregation unit forcombining the multiple signals from the multiple communication sourcesinto the combined signal. The RF processing unit together with theconversion and link aggregation unit herein, in the downlink direction,performs a conversion of signals received from the outside communicationsources (for example a demodulation) and combines several communicationlinks into a single, combined link. Within the combined signal the dataof the single communication links between the front end section and theoutside communication sources are contained and are transmitted in adata stream to the back end section for further processing andtransmission into the coverage area. Vice versa, in the uplinkdirection, the RF processing unit together with the conversion and linkaggregation unit produces multiple signals and modulates them fortransmission to the multiple communication sources.

The RF processing unit together with the conversion and link aggregationunit may, in one embodiment, be operable to equalize the multiplesignals received from the multiple communication sources in the downlinkdirection. Since communication links between the outside communicationsources and the front end section may have a different, varying linkquality (signal strength, SNIR), the equalization is performed toequalize the communication links and, hence, to bring them to acomparable level of signal strength. Such equalized communication linksmay then in an easy manner be combined (aggregated) to form the combinedsignal for a transmission to the back end section.

In the uplink direction, in turn, the RF processing unit together withthe conversion and link aggregation unit may individually gain adjustthe multiple signals for transmission to the multiple communicationsources to take into account different distances to differentcommunication sources. For this, settings of a previously performedequalization may be stored such that an individual gain adjust forindividual communication sources may be carried out based on previouslyobtained equalization information.

In one embodiment, the front end section is constituted as a host unitand the back end section is constituted by one or multiple remote unitsremote from the host unit. The front end section hence may be placed ata central location, for example on a train, a plane, a ship, a bus orthe like or on a building or a tunnel. The back end section with itsmultiple remote units in turn may be distributed over the coverage areaand hence may be placed at different locations throughout the coveragearea, for example throughout a train or a building. By means of suchdistributed remote units hence a distributed coverage may be provided.

The communication between the front end section and the back end sectionmay be established in different ways. For example, the host unit of thefront end section may communicate with the remote units of the back endsection via wireless communication connections, for example via WiFiconnections. Instead of a wireless communication connection, also wireline communication connections could be used, hence connecting the hostunit of the front end section to one or multiple remote units of theback end section making use of a wire line, for example copper cables oran optical fiber. Via the communication connections the combined signalis then transmitted to and received from the back end section.

The back end section, in the downlink direction, may be operable tomodulate the combined signal according to at least one modulation schemeto produce the RF communication signal for a transmission into thecoverage area. The back end section hence modulates the data streamobtained by means of the combined signal according to one or multiplemodulation schemes. For this, the back end section may comprise a numberof different (logical) base stations, each of which is constituted tomodulate a portion of the data stream according to a particularmodulation scheme for transmission into the coverage area. Each(logical) base station hence provides coverage in the coverage area fora particular modulation scheme (e.g. GSM, 3G, LTE or the like).

Vice versa, in the uplink direction the back end section may be operableto demodulate a received RF communication signal to produce a combinedsignal for transmission to the front end section.

The back end section, in one embodiment, further may comprise amultiplexer for multiplexing, in the downlink direction, modulatedsignals produced from the combined signals to form the RF communicationsignal for a transmission into the coverage area. The multiplexer henceforms a common communication signal, which may be transmitted via anappropriate antenna or antenna system, for example a distributed antennasystem or a so called leaky feeder, into the coverage area.

The operation in the uplink direction essentially works in an analogousfashion. A common communication signal received out of the coverage areais de-multiplexed by means of a de-multiplexer and led to the (logical)base stations of the back end section, in which a demodulation takesplace. The demodulated signals are then combined to form a combinedsignal and are forwarded to the front end section, in which signals fora transmission to the outside communication sources are produced.

In one embodiment, the front end section is operable to communicate withthe at least one communication source via a mobile communication scheme,such as GSM, GPRS, 3G, HSPA, HSPA+, LTE or WiFi. The front end sectionhence communicates with the outside communication sources via an airinterface making use of a known mobile communication scheme applying aparticular, standardized modulation.

In addition or alternatively, the front end section may also be operableto communicate with one or multiple outside communication sources via abackhaul. Such backhaul may be, but is not limited to, an IP mobilebackhaul via for example copper cables using traditional E1/T1 servicesor using DSL services, a passive optical network (PON), an activeoptical Ethernet, a fixed wireless (i.e. a fixed wireless connectionbetween two locations employing a radio or other wireless link such as alaser bridge), free-space-optical communication (FSO), radiofrequencyvia an air interface, radiofrequency directly out of a base station, orany other digital base station interfaces like CPRI.

A modulation scheme employed for a communication link between an outsidecommunication source and the front end section herein may be differentthan a modulation scheme employed for the RF communication signaltransmitted to and received from the coverage area. The back end sectionmay communicate with terminals located in the coverage area for examplevia the air (so called air interface). A modulation scheme employed forproducing the common RF communication signal may for example adhere tothe GSM, GPRS, 3G, HSPA, HSPA+, LTE or WiFi standard.

In one embodiment, the signals received from and transmitted to theoutside communication sources and the RF communication signaltransmitted into and received out of the coverage area use differentfrequency bands. The communication links between the front end sectionand the outside communication sources and the communication signaltransmitted from the back end section to terminals located in thecoverage area hence are distinct in their frequency bands, such thatinterference of signals of the communication links between the front endsection and the outside communication sources with communication signalswithin the coverage area is avoided or at least kept to a minimum.

In principle it however is also possible that the communication linksbetween the front end section and the outside communication sources andthe common RF communication signal transmitted by the back end sectioninto the coverage area at least partially use one or multiple commonfrequency bands. In that case, if the coverage area lies within ashielded, isolated environment, there may be small or no interferencebetween the outside communication links and communication links in thecoverage area. If the coverage area however does not lie in an isolated,shielded environment, it should be made sure that the signal strength ofsignals transmitted into the coverage area by means of the back endsection is limited such that the RF communication signal transmittedinto the coverage area does not interfere with the outside signals. Thisin general does not pose a problem since for example passengers in apassenger train or another moving environment are seated close toantennas of for example a distributed antenna system or close to leakyfeeder cable, such that a communication signal having limited signalstrength generally is sufficient.

The object furthermore is achieved by means of a method for operating arepeater system. The repeater system herein comprises:

-   -   a front end section which, in a downlink direction, receives        signals from at least one communication source located outside        of a coverage area of the repeater system and, in an uplink        direction, transmits signals to the at least one communication        source and    -   a back end section which, in the downlink direction, transmits        an RF communication signal into the coverage area and, in the        uplink direction, receives an RF communication signal out of the        coverage area.

Herein it is provided that

-   -   in the downlink direction the front end section combines        multiple signals from multiple communication sources into a        combined signal and transmits the combined signal to the back        end section, wherein the back end section produces, from the        combined signal, the RF communication signal for a transmission        into the coverage area and    -   in the uplink direction the back end section produces, from a        received RF communication signal, a combined signal and the        front end section produces multiple signals from the combined        signal received from the back end section for a transmission to        the multiple communication sources.

The advantages and advantageous embodiments described above with regardto the repeater system equally are applicable also to the method foroperating the repeater system, such that it shall be referred to theabove.

By means of the repeater system a local roaming cell corresponding tothe coverage area is provided for obtaining coverage in the coveragearea. Herein, instead of retransmitting signals into the coverage areaof the same kind as received from outside communication sources, anavailable capacity from communication links with outside communicationsources is collected and summed up to produce a common RF communicationsignal for transmission into the coverage area. This common RFcommunication signal may be distributed in the coverage area for exampleby a distributed antenna system or by a leaky feeder or by multipleremote units each comprising an antenna.

Such (small) local roaming cells may for example be used in moveableenvironments, such as trains, planes, ships, busses or the like or instationary environments, such as buildings (malls, campuses, officebuildings etc.) or tunnels or the like.

By providing such a local roaming cell base band, intermediate frequencyband and radio frequency band signals may be combined to a common RFcommunication signal. Such common RF communication signal can then beused to provide coverage in one or multiple roaming cells which aresomehow shielded from outside communication sources.

By means of such approach a homogeneous data rate for users in the localroaming cell may be provided. In particular, users having subscribed toservices of an operator are not bound to the backhaul performance ofsuch operator, but may obtain an improved data rate due to the linkaggregation leading to a combining of communication links of multipleoperators.

Further, within the local roaming cell advanced modulation schemes maybe employed and the full available bandwidth may be used, allowing forhigh data rates in the local roaming cell.

In addition, because a terminal located in the coverage area establishesa communication link only to the repeater system, which thencommunicates with outside communication sources, the terminal must notperform a handover. If a handover for a particular communication linkbetween an outside communication source and the repeater system isrequired, a terminal in general will not notice, because the hand oversolely takes place between the front end section of the repeater systemand outside communication sources.

The idea underlying the invention shall subsequently be described inmore detail with respect to the embodiments shown in the Figures.Herein:

FIG. 1 shows in a schematic view a repeater system in a mobileenvironment of a train in communication with outside communicationsources in the shape of base stations;

FIG. 2 a schematic view of an embodiment of a repeater system;

FIG. 3A a schematic view of frequency bands of communication links ofoutside communication sources;

FIG. 3B a schematic view of frequency bands of a communication signaltransmitted into a coverage area of the repeater system;

FIG. 4 a schematic view of another example of frequency bands of acommunication signal transmitted into the coverage area of the repeatersystem; and

FIG. 5 a schematic view of an embodiment of a repeater system connectedwith multiple different outside communication sources.

FIG. 1 shows in a schematic view a setup of a repeater system 1 on atrain 2, the repeater system 1 being in communication connection withoutside communication sources 3, 4 in the shape of base stations. Therepeater system 1 herein serves to provide coverage in a coverage area20 on the inside of the train 2 and, for this purpose, is constituted totranslate communication links 30, 40 into a communication signal to bedistributed in the coverage area 20.

An embodiment of such a repeater system 1 is schematically shown in FIG.2. The repeater system 1 comprises a front end section 10 having anantenna 100 and an RF processing unit 101 for receiving RF signals fromand transmitting RF signals 2 to outside communication sources 3, 4 viaRF communication links 30, 40. In the particular example of FIG. 2 therepeater system 1 is set up to communicate with the outsidecommunication sources 3, 4 via the air, i.e. wirelessly by means of RFsignals.

The repeater system 1 further comprises a back end section in the shapeof one or multiple remote units 13, 14 being in communication connectionwith the front end section 10 and serving to provide coverage in thecoverage area 20. The remote units 13, 14 comprise antennas 135, 143 forestablishing communication links 50, 60 to terminals 5, 6 located in thecoverage area 20.

The repeater system 1 provides a local roaming cell corresponding to thecoverage area 20. For this, instead of retransmitting the same kind ofsignals that have been received via communication links 30, 40 fromoutside sources 3, 4 into the coverage area 20, the available capacityof communication links 30, 40 is aggregated to form a common RFcommunication signal for transmission into the coverage area 20 via theremote units 13, 14. This common RF communication signal, potentiallyhaving a unique identifier, is distributed within the coverage area 20such that a combined common RF communication signal is radiated into thecoverage area 20.

For this, in a downlink direction signals of communication links 30, 40are received via antenna 100 and RF processing unit 101 at the front endsection 10. The RF processing unit 101 herein serves to perform afiltering and amplification of incoming RF signals and to forward suchsignals to a conversion and link aggregation unit 102.

In the conversion and link aggregation unit 102 the signals associatedwith the communication links 30, 40 are demodulated, converted andcombined to obtain, by means of link aggregation, a combined signalwhich, essentially, is represented by the pure data contained in thesignals of the communication links 30, 40. Such combined signal is thenprovided to the one or multiple remote units 13, 14.

In the depicted embodiment the front end section 10 is constituted as ahost unit, which for example may be located at a central location of ashielded or isolated environment such as train 2. From the front endsection 10 in the shape of the host unit the combined signal istransmitted to one or multiple remote units 13, 14 (together forming theback end section), wherein multiple remote units 13, 14 may bedistributed throughout the shielded or isolated environment such astrain 2 for providing distributed coverage in the coverage area 20.

In principle, different possibilities for establishing a connectionbetween the front end section 10 in the shape of the host unit and theremote units 13, 14 of the back end section are conceivable.

In a first example, shown in FIG. 2 on the left, the conversion and linkaggregation unit 102 of the front end section 10 may provide thecombined signal to a wireless communication unit 103 for establishing awireless connection 11 to a wireless communication unit 131 of anassociated remote unit 13. The wireless communication link 11 herein maybe a WiFi link, wherein signals are wirelessly transmitted betweenantennas 104, 130 of the host unit of the front end section 10 on theone hand and the remote unit 13 of the back end section on the otherhand.

Via the wireless communication unit 103 of the front end section 10multiple remote units 13 may be connected to the host unit of the frontend section 10.

In a second example, the host unit of the front end section 10 may beconnected to one or multiple remote units 14 by means of one or multiplewire line communication connections 12. For this, the conversion andlink aggregation unit 102 of the front end section 10, via a connection106, provides the combined signal to a splitter 105 of the front endsection 10, via which the combined signal is split and via wire linecommunication connections 12 distributed to one or multiple remote units14.

In this regard, different kinds of remote units 13, 14 can be used in arepeater system 1 in a combined fashion. A repeater system 1 hence maycomprise both remote units 13 being in wireless connection with the hostunit of the front end section 10 and remote units 14 being in wiredconnection with the host unit of the front end section 10.

Independent of the specific connection of a remote unit 13, 14 to thehost unit of the front end section 10, the remote unit 13, 14 comprisesa splitter 132, 140 for splitting the incoming combined signal tomultiple base stations 133 a-133 d, 141 a-141 d. Such base stations 133a-133 d, 141 a-141 d, which may be implemented on a single chip within aremote unit 13, 14, modulate portions of the incoming combined signalaccording to a predefined modulation schemes. The modulated signalsprovided by the base stations 133 a-133 d, 141 a-141 d are thenforwarded to a multiplexer 134, 142, which combines the modulatedsignals to form a common RF communication signal. The common RFcommunication signal is then transmitted via one or multiple antennas135, 143, which for example may be set up as a distributed antennasystem or a so called leaky feeder for providing distributed coveragethroughout the coverage area 20.

The repeater system 1 hence is set up to combine (aggregate)communication links 30, 40 established with outside communicationsources 3, 4 to obtain a combined signal and to transmit the combinedsignal as a common RF communication signal into the coverage area 20.The communication links contained in that RF communication signaltransmitted into the coverage area 20 herein may be of a different kindthan the outside communication links 30, 40. In particular, the commonRF communication signal transmitted into the coverage area 20 may employdifferent modulation schemes and may cover one or multiple differentfrequency bands.

This is shown in an example in FIGS. 3A and 3B. Herein FIG. 3A showsfrequency bands of communication links 30, 40 established betweenoutside communication sources 3, 4 and the front end section 10 of therepeater system 1. FIG. 3B, in turn, shows frequency bands covered bythe common RF communication signal which is to be transmitted into thecoverage area 20 by means of the remote units 13, 14 of the back endsection.

In the particular example, the signals of the communication links 30, 40lie in the frequency bands of

-   -   LTE 800 (between 791 MHz und 821 MHz),    -   GSM 900 (between 925 MHz and 960 MHz),    -   LTE 1800 (between 1805 MHz und 1880 MHz),    -   UMTS 2100 (between 2110 MHz und 2170 MHz) and    -   WiFi 2.4G (between 2.4 GHz and 2,4835 GHz).

Precisely, a first operator may be assigned one LTE 800 carrier having aband width of 10 MHz, a second operator may be assigned three UNITS 900carriers each having a band width of 5 MHz, the first operator inaddition may be assigned eight GSM 900 carriers each having a band widthof 200 kHz, a third operator may be assigned one LTE 1800 carrier havinga band width of 20 MHz, the first operator may be additionally assignedone LTE 1800 carrier having a band width of 20 MHz, and a fourthoperator may be assigned a UMTS 2100 carrier having a band width of 15MHz. In addition a single WiFi 2.4G 40 MHz carrier is present.

Such communication links 30, 40 hence represent data links fortransmitting data (e.g. LTE, UMTS, WiFi) or voice call links fortransmitting speech data (e.g. GSM). Such communication links 30, 40are, in the front end section 10, converted and combined to form acombined signal containing the data contained in the singlecommunication links 30, 40.

Such combined signal is forwarded, in the downlink direction, to theremote units 13, 14, which modulate by means of their base stations 133a-133 d, 141 a-141 d the combined signal to provide a localcommunication cell in the coverage area 20 employing, in the example ofFIG. 3B, the schemes of

-   -   LTE 2.6 (in a frequency band between 2620 MHz and 2680 MHz),    -   LTE3.5 (in a frequency band between 3510 MHz and 3590 MHz) and    -   WiFi 5G (in a frequency band between 5.15 GHz and 5.85 GHz).

In the particular example, data and speech carriers in the frequencybands of the communication links 30, 40 with the outside communicationsources 3, 4 hence are translated into two LTE 2.6 carriers having of aband width of 20 MHz each, two LTE 3.5 carriers having a band width of20 MHz each, and one WiFi 5G carrier having a band width of 40 MHz. Thesignals of such carriers are combined by a multiplexer 134, 142 andtransmitted as a common RF communication signal into the coverage area20 for reception by one or multiple terminals 5, 6 located in thecoverage area 20.

Terminals 5, 6 located in the coverage area 20 may for example be mobilephones, such as smartphones, or portable computer devices, such aslaptop or tablet computers. Herein, in the particular example given inFIG. 3B, via the LTE 2.6 and LTE 3.5 carriers in particular mobilephones may establish a connection to the repeater system 1, whereascomputer devices, such as laptops or tablets, may communicate with therepeater system 1 via the WiFi carrier (with an appropriate chip set orUSB dongle it may also be possible for laptops or tablets to communicatevia the LTE carriers).

The carriers of the outside communication links 30, 40 may belong todifferent operators. By means of the repeater system 1 the signals ofsuch carriers are combined to an RF communication signal common to alloperators such that a user may communicate with the repeater system 1and via the repeater system 1 with outside communication sources 3, 4substantially independent on the communication capacity of a particularoperator the user has subscribed with.

In the example of FIGS. 3A and 3B, the frequency bands of the outsidecommunication links 30, 40 and the local roaming cell in the coveragearea 20 are different from each other. It however is also possible, asshown in FIG. 4, that the frequency bands of the outside communicationlinks 30, 40 and the common RF communication signal in the coverage area20 partially or fully overlap.

In the particular example of FIG. 4, the communication signal istransmitted into the coverage area 20 via GSM/LTE 1800 carriers in thefrequency band of 1805 MHz to 1880 MHz, via UMTS 2100 carriers in thefrequency band of 2110 and 2170 MHz and via a WiFi 2.4G carrier in thefrequency band between 2.4 GHz and 2.4835 GHz. Precisely, eight GSM 1800carriers having a band width of 200 kHz each, two LTE 1800 carriershaving a band width of 20 MHz each, three UMTS 2100 carriers having aband width of 15 MHz each, and one WiFi 2.4G carrier having a band widthof 40 MHz are employed. Such frequency bands are at least in a partialmatch with a subset of the frequency bands of the outside communicationlinks 30, 40 as shown in FIG. 3A.

In this case, interference will not be a problem if the coverage area 20of the common RF communication signal transmitted by the remote units13, 14 lies in an isolated, shielded environment.

If however the environment of the coverage area 20 is not fullyshielded, it is to be made sure that the signal strength of the RFcommunication signal transmitted into the coverage area 20 is limited inorder not to interfere with outside signals. This in general poses noproblem since for example passengers in a train 2 usually are seatedclose to antennas or leaky feeder cables, such that an RF communicationsignal of limited signal strength in general is sufficient.

In the above description it primarily has been referred to the downlinkin the direction from outside communication sources 3, 4 to terminals 5,6 located in the coverage area 20. The uplink works essentially in anopposite fashion in that in the uplink direction in the remote units 13,14 a combined signal is produced and forwarded to the front end section10, and the conversion and link aggregation unit 102 of the front endsection 10 translates the combined signal into signals for the differentoutside communication links 30, 40. The RF processing unit 101 thentransmits, via antenna 100, corresponding RF signals to thecommunication sources 3, 4.

In the example of FIGS. 1 to 4, outside communication sources 3, 4communicate via an air interface with the repeater system 1. This inparticular is applicable for moving environments such as trains, planes,ships or vehicles such as busses. A repeater system 1 of the kinddescribed herein however may also be used in stationary environmentssuch as in buildings or tunnels for providing coverage in isolated areasof such environments.

For such stationary environments it is also conceivable, as shown in anembodiment in FIG. 5, that the repeater system 1 via a backhaul 96 isdirectly connected to outside communication sources 9 of communicationnetworks. For example, via backhaul 96 the front end section 10 of therepeater system 1 may be connected to a communication source providingE1/T1 services 90, to a communication source providing DSL services 91,to a passive optical network (PON) 92, to an active optical Ethernet 93,to a free-space optical communication network 94, or to a fixed wirelesscommunication link 95. Via such backhaul 96 data may, in the digitalbaseband, be provided directly to the conversion and link aggregationunit 102.

Further, a communication source 8 in the shape of a base station may beconnected via a so called Common Public Radio Interface (CPRI) to theconversion and link aggregation unit 102 of the front end section 10.

In addition, a communication source 7 may via an RF cable be connectedto the RF processing unit 101, hence providing RF signals in the RFfrequency band to the RF processing unit.

By means of the conversion and link aggregation unit 102 such differentsignals are combined to a single combined signal containing the datacomprised in the several communication links. The distribution of thecommunication data stream within the coverage area 20 takes placesimilarly as described above.

The idea underlying the invention is not limited to the embodimentsdescribed above, but may be implemented in an entirely different fashionin completely other solutions.

In particular, a repeater system of the noted kind may operate inentirely different environments than the ones stated above. Further,entirely different modulation schemes and/or frequency bands may beemployed other than the ones mentioned in this text.

LIST OF REFERENCE NUMERALS

-   -   1 Repeater system    -   10 Front end section (host unit)    -   100 Antenna    -   101 RF processing unit    -   102 Conversion and link aggregation unit    -   103 Wireless communication unit    -   104 Antenna    -   105 Splitter    -   106 Connection line    -   11 Wireless communication connection    -   12 Wire line communication connection    -   13 Back end section (remote unit)    -   130 Antenna    -   131 Wireless communication unit    -   132 Splitter    -   133 a-133 c Remote base station    -   133 d WiFi hub    -   134 Multiplexer    -   135 Antenna port    -   14 Back end section (remote unit)    -   140 Splitter    -   141 a-141 c Remote base station    -   141 d WiFi hub    -   142 Multiplexer    -   143 Antenna port    -   2 Train    -   20 Coverage area    -   3, 4 Base station    -   30, 40 Communication link    -   5, 6 Terminal    -   50, 60 Communication link    -   7, 8 Base station    -   9 Signal sources    -   90-95 Signal source    -   96 Backhaul

What is claimed is:
 1. A repeater system located within a coverage area,the repeater system comprising: a host unit configured to combinemultiple downlink signals from multiple communication sources locatedoutside the coverage area into a first combined downlink signal; atleast one remote unit coupled to the host unit and configured totransmit the first combined downlink signal as a second downlink RFcommunication signal into the coverage area to a plurality of userterminals located within the coverage area; wherein the at least oneremote unit is further configured to produce a combined uplink signalfrom multiple uplink signals received through multiple communicationlinks from the plurality of user terminals located within the coveragearea, and further configured to forward the combined uplink signal tothe host unit; wherein the host unit is configured to produce multiplesignals from the combined uplink signal for transmission to the multiplecommunication sources; wherein a first of the plurality of userterminals communicates with a different one of the multiplecommunication sources than a second of the plurality of user terminals.2. The repeater system of claim 1, wherein the host unit comprises aconversion and link aggregation unit configured to combine the pluralityof downlink signals from the multiple communication sources into thecombined downlink signal.
 3. The repeater system of claim 2, wherein theconversion and link aggregation unit is further configured to producethe plurality of uplink signals and modulate the plurality of uplinksignals for transmission to the multiple communication sources.
 4. Therepeater system of claim 3, wherein the host unit further comprises anRF processing unit, communicatively coupled to the conversion and linkaggregation unit, the RF processing unit configured to equalize theplurality of downlink signals received from the multiple communicationsources, and individually gain adjust the plurality of uplink signalsfor transmission to the multiple communication sources.
 5. The repeatersystem of claim 1, wherein the at least one remote unit furthercomprises: a plurality of base stations each configured to receive thecombined downlink signal from the host unit and modulate a portion ofthe combined downlink signal according to at least one modulation schemeto produce an RF communication signal; and a multiplexer that combinesthe RF communication signal from each of the plurality of base stationsto form the second downlink RF communication signal for transmissioninto the coverage area.
 6. The repeater system of claim 1, wherein thehost unit is configured to communicate with multiple communicationsources over an air interface.
 7. The repeater system of claim 1,wherein the host unit is configured to communicate with the multiplecommunication sources via a mobile communication scheme.
 8. The repeatersystem of claim 7, wherein the mobile communication scheme is at leastone of GSM, GPRS, 3G, HSPA, HSPA+, LTE, and WiFi.
 9. The repeater systemof claim 1, wherein the host unit is configured to communicate with themultiple communication sources each via a different respective mobilecommunication scheme.
 10. The repeater system of claim 1, wherein thehost unit is configured to communicate with at least one of the multiplecommunication sources via a backhaul.
 11. The repeater system of claim1, wherein a first modulation scheme of the multiple downlink signalsreceived from the multiple communication sources is different than asecond modulation scheme of the second downlink RF communication signaltransmitted into the coverage area.
 12. The repeater system of claim 1,wherein a modulation scheme of the second downlink RF communicationsignal transmitted into the coverage area comprises is at least one ofGSM, GPRS, 3G, HSPA, HSPA+, LTE, and WiFi.
 13. The repeater system ofclaim 1, wherein the second downlink RF communication signal transmittedinto the coverage area comprises at least two different modulationschemes.
 14. The repeater system of claim 1, wherein the multipledownlink signals from multiple communication sources and the secondcombined downlink signal operate in different frequency bands.
 15. Therepeater system of claim 1, wherein the combined uplink signal and themultiple uplink signals operate in different frequency bands.
 16. Amethod, comprising: receiving, at a host unit, a plurality of downlinksignals from multiple communication sources located outside of acoverage area, wherein the host unit is configured to combine pluralityof downlink signals from multiple communication sources into a firstcombined downlink signal for transmission to one or more remote units;transmitting from each of the one or more remote units a second combineddownlink RF communication signal into the coverage area to a pluralityof user terminals located within the coverage area, wherein the seconddownlink RF communication signal is produced from the first combineddownlink signal; producing at each of the one or more remote units acombined uplink signal from multiple uplink signals received throughmultiple communication links from the plurality of user terminalslocated within the coverage area; transmitting a plurality of uplinksignals from the combined uplink signal for transmission to the multiplecommunication sources; wherein a first of the plurality of userterminals communicates with a different one of the multiplecommunication sources than a second of the plurality of user terminals.17. The method of claim 16, wherein the one or more remote units areeach configured for: receiving the combined downlink signal from thehost unit and modulating a portion of the combined downlink signalaccording to at least one modulation scheme to produce multiplemodulated signals; multiplexing the multiple modulated signals to formthe second downlink RF communication signal for transmission into thecoverage area.
 18. The method of claim 16, wherein the second downlinkRF communication signal transmitted into the coverage area comprises atleast two different mobile modulation schemes.
 19. The method of claim16, wherein the host unit is configured to communicate with the multiplecommunication sources each via a different respective mobilecommunication scheme.
 20. The method of claim 16, wherein the host unitis configured to communicate with at least one of the multiplecommunication sources via a backhaul.